Dialysate sodium control during modeling in hemodialysis.

Abstract

Dialysate sodium (Na+) modeling in hemodialysis requires precise individual adjustment and control of Na+ dialysate concentration. In practice, variations of Na+ concentration can be important and can affect the accuracy of Na+ modeling. Variations relate mainly to the low accuracy of dialysate concentrate (+/- 2.5% for Na+ is tolerated by the European Pharmacopeias), purity of hemodialysis water (2.17 mEq/L is the limit fixed by the French Pharmacopeia), and precision of the proportioning delivery systems for hemodialysis bath preparation. To minimize these difficulties, this study focused on the following points: (a) Na+ concentration is maintained constant (133 mEq/L) in the dialysate manufacturing unit. In 1982, 268 dialysate preparations (177,000 L) were made, and the mean value for Na+ concentration was 133.1 +/- 0.3 mEq/L with a probability of 99.9%. (b) The purity of the water, especially for Na+, Ca2+, and K+, is controlled for two times a day. (c) The accuracy of the proportioning delivery system is controlled by two conductivity monitors, and the variation of Na+ concentration around 133 mEq/L is smaller than +/- 0.5%. As the composition of the basic dialyzing fluid remains constant before adaptation, conductivity values reflect exactly Na+ variation, and are not affected by variations of other elements (K+, Ca2+, Mg2+) that may occur when modification of the dialysate is used for Na+ modeling. (d) Na+ dialysate concentration is adapted for each patient's need by a bedside monitor with sterile Na+ solutions (5 mol/L).(ABSTRACT TRUNCATED AT 250 WORDS)